Tecumseh HM80

[TKM51]

I have a Tecumseh 8hp on a snowblower . ( found unit ) It was backfiring out the exhaust . I redid the valves and re gapped them to 10mm . Started it and it is still firing through the exhaust . It is also pushing oil out through the valve cover gaskets . Pulled the head again and found a puddle of oil on the piston . Not sure how to proceed

 

[Fixr]

I have a Tecumseh 8hp on a snowblower . ( found unit ) It was backfiring out the exhaust . I redid the valves and re gapped them to 10mm . Started it and it is still firing through the exhaust . It is also pushing oil out through the valve cover gaskets . Pulled the head again and found a puddle of oil on the piston . Not sure how to proceed

I would look at an HF Predator engine.

 

[rooster59]

Maybe worn valve guides, bent valve. Might help -

https://www.allotment-garden.org/rotavator-manuals/Techumseh-L-Head-Engines-Manual.pdf

https://www.harborfreight.com/8-hp-301cc-ohv-horizontal-shaft-gas-engine-epa-62554.html

 

[Fixr]

Maybe worn valve guides, bent valve. Might help -

https://www.allotment-garden.org/rotavator-manuals/Techumseh-L-Head-Engines-Manual.pdf

https://www.harborfreight.com/8-hp-301cc-ohv-horizontal-shaft-gas-engine-epa-62554.html

The Predator engines seem to go on sale pretty frequently. I'd probably wait for that.

 

[BillK]

I redid the valves and re gapped them to 10mm .

The correct spec is .008" to .012" ??? 10MM is almost 3/8" lol ??

Valve guides will not make it push oil out of the valve cover. Probably has stuck or broken piston rings All you can do is take it apart and see. Those engines are usually pretty bulletproof. I would rather fix it any day compared to the new import stuff.

Just my opinion,

 

[TKM51]

The correct spec is .008" to .012" ??? 10MM is almost 3/8" lol ??

Valve guides will not make it push oil out of the valve cover. Probably has stuck or broken piston rings All you can do is take it apart and see. Those engines are usually pretty bulletproof. I would rather fix it any day compared to the new import stuff.

Just my opinion,

Yeah my bad I meant 010

 

[TKM51]

The Predator engines seem to go on sale pretty frequently. I'd probably wait for that.

The correct spec is .008" to .012" ??? 10MM is almost 3/8" lol ??

Valve guides will not make it push oil out of the valve cover. Probably has stuck or broken piston rings All you can do is take it apart and see. Those engines are usually pretty bulletproof. I would rather fix it any day compared to the new import stuff.

Just my opinion,

Well dismantling and fixing for something know one wants . This ole soldier isn’t carrying any plastic .It just isn’t pretty like the newer ones

 

[ToolsRCool]

I have a Tecumseh 8hp on a snowblower . ( found unit ) It was backfiring out the exhaust . I redid the valves and re gapped them to 10mm . Started it and it is still firing through the exhaust . It is also pushing oil out through the valve cover gaskets . Pulled the head again and found a puddle of oil on the piston . Not sure how to proceed

Probably sheared flywheel key, and possibly cracked flywheel @ key. Worst engine ever. Put it back where you found it.

 

[hobie18]

Probably sheared flywheel key, and possibly cracked flywheel @ key. Worst engine ever. Put it back where you found it.

Came here to say the same thing. Not disappointed.

 

[hobie18]

These old machines with the cut back front housing are loved by snowblower enthusiasts. Plenty of ideas over on the snowblower forum.
They are not top of the safety chart.
Many ways to go. Sell, fix, tinker. If the engine shaft/shafts, line up, and are single, as opposed to doing one off crank, and drive off cam, the swap is easy. And you can get a much better engine. Much. But is the rest of the machine good enough. Go over and find out.

How much snow do you get there?

 

[TKM51]

The last few years we have not received much snow . About 50 miles north they have received better than a foot in a short time These machines I bring home are a hobby . I fix and move them along. I am only looking to break even . I don’t want to pour money in beyond what the machine is worth. I am thinking I will set It aside and decide in the spring to save or scrap - thanks everyone for the help and direction .

 

[The Cobbler]

It is also pushing oil out through the valve cover gaskets .

bad rings or valve guides causing blowby, or RPM is set way too high .

 

[PoorUB]

Worst engine ever. Put it back where you found it.

It isn't a great engine, but far from the worst! They get a bad rap because the get ignored and abused. People use their snow blower and park it in the spring and leave gas in it, then it doesn't snow for a couple years and the carb gets gummed up. Or they never change or cheeck the oil and blow the connecting rod. Everyone I saw with a blown rod was way low on oil.

They run forever on a snowblower if they get a bit of maintenance. I had one on a snow blower for 15 years and had zero issues with it. When I had my shop I had HM80's come in all the time, clean the carb, grind the valves, points, condenser and properly time it and they ran like a champ. They don't get enough hours on a snow blower to wear them out. Only abuse kills them.

 

[ToolsRCool]

It isn't a great engine, but far from the worst! They get a bad rap because the get ignored and abused. People use their snow blower and park it in the spring and leave gas in it, then it doesn't snow for a couple years and the carb gets gummed up. Or they never change or cheeck the oil and blow the connecting rod. Everyone I saw with a blown rod was way low on oil.

They run forever on a snowblower if they get a bit of maintenance. I had one on a snow blower for 15 years and had zero issues with it. When I had my shop I had HM80's come in all the time, clean the carb, grind the valves, points, condenser and properly time it and they ran like a champ. They don't get enough hours on a snow blower to wear them out. Only abuse kills them.

I'll give you partial credit. Tecumseh owned the snow market way back when, 2 stroke and 4. For whatever reason, decent majority of those could run OK. But, their summer season ones were terrible. Lawn mowers, minibikes, etc... Briggs seemed to have been the preferred summer engine, and I don't think you had much choice but to have a Tecumseh in the winter.

Genuine Honda GX single cylinders for me now.....quality sent from the heavens.